Effects of substrate on prey use by belted kingfishers (Ceryle alcyon): a test of the prey abundance – availability assumption

1996 ◽  
Vol 74 (4) ◽  
pp. 693-697 ◽  
Author(s):  
Jeffrey F. Kelly
Keyword(s):  
Habitat Structure ◽  
Prey Availability ◽  
Pimephales Promelas ◽  
Prey Preference ◽  
Prey Abundance ◽  
Abundance Distribution ◽  
Dynamic Factors ◽  
Prey Resources ◽  
Ceryle Alcyon ◽  
Complex Habitat

Foraging trials were conducted using belted kingfishers (Ceryle alcyon) to examine relationships among prey abundance, availability, and use. Because these relationships are affected by the preference of the predator, I also determined the prey preference of belted kingfishers. Fish (Pimephales promelas and Catostomus commersoni) and crayfish (Orconectes spp.) were exposed to predation by 12 wild belted kingfishers under 4 treatments in which prey availability was manipulated by altering habitat structure. The preferred prey of belted kingfishers were relatively large fish (11–13 cm long). In structurally simple habitats, prey use by belted kingfishers reflected this preference. Complex habitat structure reduced the availability of preferred prey items and resulted in prey use that did not differ from the initial prey abundance distribution. These experiments demonstrated that prey abundance was not equivalent to availability and that habitat structure and prey preference had important effects on the relationships among prey abundance, availability, and use. Thus, evaluating the importance of prey resources to predators on the basis of prey abundance–use comparisons, while ignoring prey availability and the dynamic factors that influence it, may lead to erroneous conclusions.

Modelling mutual interactions between soil structure and soil biological communities.

2021 ◽  
Author(s):  
Tancredi Caruso
Keyword(s):  
Habitat Structure ◽  
Soil Structure ◽  
Pore Space ◽  
Point Of View ◽  
Species Number ◽  
Ecological Communities ◽  
Soil Organisms ◽  
Biological Communities ◽  
Key Factor ◽  
Complex Habitat

<p>Habitat structure is a key factor controlling the structure of ecological communities. For example, complex habitat structure may increase species number, minimise competition and facilitate the retention of nutrients. Alteration and disturbance of habitat structure may thus negatively affect biodiversity. Soil is an extremely complex and highly structured environmental matrix. Soil structure, defined as a distribution of aggregate/pore space of different sizes, can thus be a major control of soil biological communities, which are for example highly structured in their size distribution. Soil organisms, however, also affect and modify soil structure, and for many organisms the soil habitat structure is thus not just a condition to which they have to adapt but, rather, an environmental feature they also affect. In this talk, I discuss all these aspects from a community ecology point of view and with an emphasis on statistical and dynamical models that soil ecologists are trying to develop to describe and predict the mutual interactions between soil structure and biological communities. I will focus on the different rates at which soil structure affects soil organisms and vice versa, to emphasise that the temporal scales at which we have to measure the two parts of this mutual feedback (i.e. soil structure -> biota vs. biota -> soil structure) are very different, and also variable in space and time. </p>

scholarly journals Evidence of Predation on Nestling Birds by Eastern Gartersnakes (Thamnophis sirtalis sirtalis)

2016 ◽  
Vol 130 (2) ◽  
pp. 146 ◽  
Author(s):  
William D. Halliday
Keyword(s):  
Natural History ◽  
Food Choice ◽  
Prey Availability ◽  
Prey Preference ◽  
Thamnophis Sirtalis ◽  
Space And Time ◽  
History Of ◽  
The Common ◽  
Prey Items

Diet is an important aspect of the natural history of all animals, but diet can vary through space and time because of variations in prey availability. The diet of the Common Gartersnake (Thamnophis sirtalis) consists mainly of earthworms and frogs, but other prey items might be important when they are locally abundant. I report an observation of a female Eastern Gartersnake (Thamnophis sirtalis sirtalis) regurgitating 2 nestling birds in Ottawa, Ontario, Canada. Birds are seldom present in the diet of the Common Gartersnake. This rare food choice highlights the opportunistic nature of foraging by adult Common Gartersnakes and, further, demonstrates that diet depends not only on prey preference, but also on prey availability.

Stable foraging areas and variable chick diet in Cassin's auklets (Ptychoramphus aleuticus) off southern California

2004 ◽  
Vol 82 (10) ◽  
pp. 1578-1595 ◽  
Author(s):  
Josh Adams ◽  
John Y Takekawa ◽  
Harry R Carter
Keyword(s):  
Southern California ◽  
Prey Availability ◽  
California Current ◽  
Breeding Ecology ◽  
Foraging Area ◽  
Cassin's Auklet ◽  
Prey Resources ◽  
Ptychoramphus Aleuticus ◽  
Second Clutch ◽  
Breeding Seasons

Planktivorous seabirds readily respond to changes in marine ecosystems and have the ability to integrate information regarding variability in abundance, availability, and community composition of key prey resources. We studied the foraging and breeding ecology of the Cassin's auklet, Ptychoramphus aleuticus (Pallas, 1811), off southern California during three breeding seasons (1999–2001), when large intra- and inter-annual variability occurred in local oceanographic conditions during a prolonged La Niña event. Radio-marked parents used consistent core foraging areas within 30 km of their colony, aggregated in shelf waters (<200 m depth), and occasionally foraged in deeper waters. Parents delivered primarily euphausiids, pelagic larval-juvenile fishes, and minor amounts of cephalopods and other crustaceans. Whereas the euphausiid Thysanoessa spinifera Holmes, 1900 was most important during 1999 and 2001, Euphausia pacifica Hansen, 1911 replaced adult T. spinifera in 2000 after an anomalous eastward inflection of the California Current occurred near the auklets' foraging area. Differences in chick diets, however, did not significantly influence fledging success and growth among first chicks, but the proportion of pairs successfully fledging an alpha chick and initiating a second clutch was exceptional in 1999 (63%) and 2000 (75%), and less in 2001 (7%). We suggest that dietary composition was influenced by modified prey availability driven in part by fluctuations in regional upwelling and circulation.

scholarly journals Carnivore ecology and conservation : implications for tiger conservation and management in Nepal

2016 ◽  
Author(s):  
◽  
Hemanta Kafley
Keyword(s):  
Protected Areas ◽  
Prey Availability ◽  
Prey Abundance ◽  
Home Ranges ◽  
Large Carnivores ◽  
Conservation Programs ◽  
Intraguild Interactions ◽  
Formidable Challenge ◽  
Tiger Conservation ◽  
Conservation And Management

In human-dominated landscapes, conservation and management of large carnivores has been a formidable challenge due to habitat fragmentation, degradation and loss, wildlife persecution, and poaching. Consequently, wide-ranging species like tigers are now relegated to small protected areas. I evaluated factors influencing occupancy of tiger at a fine spatial-scale, developed a novel model to estimate prey abundance, assessed intraguild interaction between tigers and leopards in response to prey and disturbance factors, and evaluated sustainable financing mechanisms for tiger conservation programs. The success of carnivore conservation relies on better understanding their habitat use and prey availability, the community structure of competing species, and the financial ability to sustain monitoring and conservation programs. I collected field data through camera trap survey in Chitwan National Park and found that tiger occurrence was influenced by fine-scale habitat factors including prey availability. I concluded that in small protected areas wide-ranging carnivores may persist at high population densities by intensively focusing their activity on small portions of their home ranges. Furthermore, prey abundance, key to carnivore persistence, can be reliably estimated from camera trapping data using binomial mixture models. Further, prey abundances in conjunction with human and livestock presence in the park modulate intraguild interactions between tigers and leopards. Collectively, these findings should provide useful information for biologists, conservationists, and managers on how to successfully conserve and manage large carnivores.

scholarly journals The consequences of complex habitat loss for the New Zealand blue cod, Parapercis colias

2021 ◽  
Author(s):  
◽  
Baylee Wade
Keyword(s):  
Population Dynamics ◽  
New Zealand ◽  
Predation Risk ◽  
Habitat Loss ◽  
Habitat Complexity ◽  
Prey Availability ◽  
Prey Abundance ◽  
Foraging Success ◽  
Trade Off ◽  
Fishery Species

<p>Climate driven threats are predicted to decrease the complexity of biogenic habitats. Within temperate coastal marine environments, we know that complex macroalgal beds support more complex communities through the provision of microhabitats and refuges. Macroalgal habitats have potential interacting benefits and costs for predators, as increased macroalgal biomass supports higher richness and diversity of prey species, but prey within these habitats might be more difficult to catch. An important New Zealand fishery species, the blue cod (Parapercis colias), is a large bodied temperate reef fish found exclusively throughout the coastal waters of New Zealand. Its dependence on subtidal coastal reef environments mean that it is important to understand how a loss of complex macroalgal habitats might alter the way that blue cod forage, and how the trade-off between prey abundance and availability will affect its abundance and productivity. This thesis aims to understand the influence of complex macroalgal habitats on P. colias prey availability and behaviour, on the foraging success of P. colias, and ultimately on P. colias population dynamics. Experiments were conducted using choice chambers to evaluate whether two alternate P. colias prey, Forsterygion lapillum and Heterozius rotundifrons, showed a preference for complex habitats with and without predation risk. Both species preferred complex habitats in the absence of predation cues, but F. lapillum showed a more consistent preference for complexity in response to predation risk. A mesocosm experiment was used to investigate whether the consumption rate and functional response of P. colias differs for these two prey types in the presence and absence of habitat complexity. Results indicated that the mobile fish prey, F. lapillum benefitted from the refuges provided by complexity and suffered lower consumption rates, whereas the sedentary crab, H. rotundifrons did not. Finally, using a simple population model, the trade-off between prey abundance and predation success on the population dynamics of P. colias with and without habitat complexity was explored. Models showed that scenarios with complex macroalgal habitats generally support more predators, and faster population growth rates than scenarios lacking habitat complexity. However, scenarios with complex habitats were predicted to be more sensitive to fishing pressure and have the potential to be more vulnerable to overexploitation. These results highlight the importance of understanding how habitat complexity mediates relationships between commercially important fishery species and their prey, in order to understand how habitat loss may alter their foraging success and population dynamics.</p>

Prey size and availability limits maximum size of rainbow trout in a large tailwater: insights from a drift-foraging bioenergetics model

2016 ◽  
Vol 73 (5) ◽  
pp. 759-772 ◽  
Author(s):  
Michael J. Dodrill ◽  
Charles B. Yackulic ◽  
Theodore A. Kennedy ◽  
John W. Hayes
Keyword(s):  
Rainbow Trout ◽  
Prey Size ◽  
Prey Availability ◽  
Maximum Size ◽  
Large Prey ◽  
Bioenergetics Model ◽  
Prey Biomass ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Temperature Regimes ◽  
Prey Resources

The cold and clear water conditions present below many large dams create ideal conditions for the development of economically important salmonid fisheries. Many of these tailwater fisheries have experienced declines in the abundance and condition of large trout species, yet the causes of these declines remain uncertain. Here, we develop, assess, and apply a drift-foraging bioenergetics model to identify the factors limiting rainbow trout (Oncorhynchus mykiss) growth in a large tailwater. We explored the relative importance of temperature, prey quantity, and prey size by constructing scenarios where these variables, both singly and in combination, were altered. Predicted growth matched empirical mass-at-age estimates, particularly for younger ages, demonstrating that the model accurately describes how current temperature and prey conditions interact to determine rainbow trout growth. Modeling scenarios that artificially inflated prey size and abundance demonstrate that rainbow trout growth is limited by the scarcity of large prey items and overall prey availability. For example, shifting 10% of the prey biomass to the 13 mm (large) length class, without increasing overall prey biomass, increased lifetime maximum mass of rainbow trout by 88%. Additionally, warmer temperatures resulted in lower predicted growth at current and lower levels of prey availability; however, growth was similar across all temperatures at higher levels of prey availability. Climate change will likely alter flow and temperature regimes in large rivers with corresponding changes to invertebrate prey resources used by fish. Broader application of drift-foraging bioenergetics models to build a mechanistic understanding of how changes to habitat conditions and prey resources affect growth of salmonids will benefit management of tailwater fisheries.

scholarly journals Drivers of red fox (Vulpes vulpes) daily activity: prey availability, human disturbance or habitat structure?

2015 ◽  
Vol 298 (2) ◽  
pp. 128-138 ◽  
Author(s):  
F. Díaz-Ruiz ◽  
J. Caro ◽  
M. Delibes-Mateos ◽  
B. Arroyo ◽  
P. Ferreras
Keyword(s):  
Human Disturbance ◽  
Daily Activity ◽  
Vulpes Vulpes ◽  
Habitat Structure ◽  
Red Fox ◽  
Prey Availability

scholarly journals Contrasting effects of rising temperatures on trophic interactions in marine ecosystems

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Joël M. Durant ◽  
Juan-Carlos Molinero ◽  
Geir Ottersen ◽  
Gabriel Reygondeau ◽  
Leif Christian Stige ◽  
...  
Keyword(s):  
Prey Availability ◽  
Strong Dependence ◽  
Population Decline ◽  
Fish Population ◽  
Prey Abundance ◽  
Light Cycle ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Water Column Stability ◽  
Zooplankton Prey

Abstract In high-latitude marine environments, primary producers and their consumers show seasonal peaks of abundance in response to annual light cycle, water column stability and nutrient availability. Predatory species have adapted to this pattern by synchronising life-history events such as reproduction with prey availability. However, changing temperatures may pose unprecedented challenges by decoupling the predator-prey interactions. Here we build a predator-prey model accounting for the full life-cycle of fish and zooplankton including their phenology. The model assumes that fish production is bottom-up controlled by zooplankton prey abundance and match or mismatch between predator and prey phenology, and is parameterised based on empirical findings of how climate influences phenology and prey abundance. With this model, we project possible climate-warming effects on match-mismatch dynamics in Arcto-boreal and temperate biomes. We find a strong dependence on synchrony with zooplankton prey in the Arcto-boreal fish population, pointing towards a possible pronounced population decline with warming because of frequent desynchronization with its zooplankton prey. In contrast, the temperate fish population appears better able to track changes in prey timing and hence avoid strong population decline. These results underline that climate change may enhance the risks of predator-prey seasonal asynchrony and fish population declines at higher latitudes.

Latitudinal variation in the geometric morphology of the largemouth bass, Micropterus salmoides

2018 ◽  
Vol 69 (9) ◽  
pp. 1480 ◽  
Author(s):  
Elijah S. Hall ◽  
Benjamin E. Martin ◽  
Kristen Brubaker ◽  
Christopher J. Grant
Keyword(s):  
Largemouth Bass ◽  
Habitat Structure ◽  
Body Shape ◽  
Prey Availability ◽  
Abiotic Factors ◽  
Micropterus Salmoides ◽  
Canonical Variate ◽  
Resource Utilisation ◽  
Eastern United States ◽  
Geometric Morphology

Geometric morphology can be influenced by several biotic and abiotic factors, including predator–prey interactions and habitat structure. We measured the external morphology of Micropterus salmoides (largemouth bass, LMB) from two states in north-eastern United States, to assess the potential divergence of body shape. LMB varied in overall body shape (canonical variate analysis, P<0.001) between states, with Maine populations exhibiting shorter jaws (ANOVA, P<0.001) and thicker caudal peduncle depths (ANOVA, P<0.001) than the LMB in Pennsylvania. We propose that these observed differences in morphological traits suggest that jaw length may be influenced by prey availability and resource utilisation, whereas peduncle depth is better explained by surrounding habitat structure. These findings showed that body shape is variable and is influenced by a complex array of environmental factors, even over small latitudinal differences.

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